如何查找字符串vb.net中子字符串的出现次数

Question

我有一个字符串(例如:) "Hello there. My name is John. I work very hard. Hello there!",我试图找到字符串的出现次数"hello there".到目前为止,这是我的代码:

Dim input as String = "Hello there. My name is John. I work very hard. Hello there!"
Dim phrase as String = "hello there"
Dim Occurrences As Integer = 0

If input.toLower.Contains(phrase) = True Then
    Occurrences = input.Split(phrase).Length      
    'REM: Do stuff
End If

不幸的是,这行代码似乎是在每次看到第一个字母时分割字符串phrase,在本例中h.因此Occurrences = 2,我实际上得到的数字要大得多,而不是我希望得到的结果.我知道计算一个字符串中的分裂数是一种可怕的方式,即使我得到了正确的答案,所以有人可以帮助我并提供一些帮助吗？

Answer 1

另一个想法:

Dim input As String = "Hello there. My name is John. I work very hard. Hello there!"
Dim phrase As String = "Hello there"
Dim Occurrences As Integer = (input.Length - input.Replace(phrase, String.Empty).Length) / phrase.Length

你只需要确保这一点phrase.Length > 0.

Answer 2

最好的方法是:

Public Function countString(ByVal inputString As String, ByVal stringToBeSearchedInsideTheInputString as String) As Integer
    Return System.Text.RegularExpressions.Regex.Split(inputString, stringToBeSearchedInsideTheInputString).Length -1

End Function

Answer 3

str="Thisissumlivinginsumgjhvgsum in the sum bcoz sum ot ih sum"
b= LCase(str)
array1=Split(b,"sum")
l=Ubound(array1)
msgbox l

输出给了你编号。一个字符串在另一个字符串中出现的次数。

Answer 4

您可以创建一个 Do Until 循环，一旦整数变量等于您正在检查的字符串的长度，该循环就会停止。如果该短语存在，则增加出现次数，并将该短语的长度加上找到该短语的位置添加到光标变量中。如果找不到该短语，则搜索完成（不再有结果），因此将其设置为目标字符串的长度。为了不对相同的出现次数进行多次计数，请仅检查从光标到循环中目标字符串的长度 (strCheckThisString)。

    Dim input As String = "hello there. this is a test. hello there hello there!"
    Dim phrase As String = "hello there"
    Dim Occurrences As Integer = 0

    Dim intCursor As Integer = 0
    Do Until intCursor >= input.Length

        Dim strCheckThisString As String = Mid(LCase(input), intCursor + 1, (Len(input) - intCursor))

        Dim intPlaceOfPhrase As Integer = InStr(strCheckThisString, phrase)
        If intPlaceOfPhrase > 0 Then

            Occurrences += 1
            intCursor += (intPlaceOfPhrase + Len(phrase) - 1)

        Else

            intCursor = input.Length

        End If

    Loop